The banks of London's "dirty old river" Thames are being transformed into the golden sands of Bondi beach, to promote NSW.

The G'Day UK campaign aims to promote not only tourism but also Australian innovation and industry.

Eighty tonnes of sand has been dumped beside the Thames to recreate the iconic beach, complete with lifeguards, surfboards and deck chairs.

As part of the campaign, NSW will head an innovative showcase of eight Sydney companies in London on Friday.

State development minister Ian Macdonald on Tuesday said the event would give these Sydney companies a chance to win new business and encourage British companies to invest in them.

"These companies are representative of the cutting-edge technologies that are being developed in NSW and include security and surveillance systems, solar technology, cancer detection and wave energy conversion," he said.

NSW's participation in G'Day UK was part of the Government's strategy to promote the state's strengths on the international stage and to encourage investment in the state, Mr Macdonald said .

"NSW has had a long commercial relationship with the United Kingdom. It's the sixth largest economy in the world and so remains a very important market for us.

G'Day UK will run until Tuesday and will also include an exhibition by the Victorian government, taking visitors through the sights and sounds of Melbourne, and a South Australian wine tasting event.